The present invention relates to surface contour and thickness measuring devices and, more particularly, to surface profile and thickness measuring devices utilizing non-contact components such as lasers.
In the manufacturing industry, it is often necessary to measure deviations and surface profile of a workpiece, such as a sheet of rolled metal material, or a coil of sheet material. Mechanical devices have been used in which a carriage traverses the width of the object whose surface profile is to measured, and an arm or probe contacts the surface. The carriage moves along a straight line, and deviation in the surface contour cause the contacting arm to pivot relative to the carriage. This pivoting movement is recorded, either mechanically by means of a pen and graph arrangement or the like, or electronically by means of motion transducers. An example of such a device is shown in U.S. Pat. No. 4,403,419, issued Sep. 13, 1983.
A second generation of measuring devices has been developed in which a laser is used to provide a reference line or base line. Such a system is manufactured by Fixture-Laser ab of Sweden and includes a laser transmitter and a laser detector. The laser is capable of detecting changes in the position of a detector which is directed to its detecting surface. In order to detect deviations in surface profile, the laser transmitter generates a laser which extends substantially parallel to the surface to be measured, and the laser detector is moved along the surface.
Deviation of the detector along the surface relative to the directed laser generates a digital signal which can be recorded. However, such systems still rely upon physical contact between the surface to be measured and the measuring device. Such physical contact can have a negative effect on the accuracy of the measurements taken, and cannot be used to measure any substance that deviates on contact.
Accordingly, there is a need for a measurement system in which physical contact between the measurement apparatus and the surface to be measure is eliminated, and which is highly accurate.